1. Field of the Invention
The present invention generally involves the field of technology pertaining to gas burners. More specifically, the invention relates to an improved sealed gas burner assembly provided with spark ignition.
2. Description of the Prior Art
A sealed gas burner assembly is received in the burner opening of a range top and secured in place around the periphery of the opening so that any spillage of food during the cooking process cannot pass between the burner assembly and range top and into the burner box below the range top. This type of burner assembly improves upon earlier known gas burners wherein a large annular spacing exists between the burner head and peripheral edge of the burner opening in the range top. The configuration of a sealed burner assembly provides a clean streamlined appearance which facilitates the cleaning and maintenance of the range top.
A sealed burner assembly typically includes a burner cap provided with a sidewall having a plurality of burner ports formed therein and through which the primary air/gas mixture is passed to the exterior of the cap for combustion. An electrode connected to an appropriate electrical circuit extends through the sidewall of the cap for providing spark ignition of the mixture. The use of spark ignition has become increasingly used because it avoids the extra energy consumption required by a standing igniter pilot flame that is often used to ignite gas range top burners. The electrode may be in the form of a wire which extends upwardly through the base of the burner assembly and supported therein by an electrically insulative member, and outwardly through an electrode aperture in the sidewall of the burner cap within which it is supported by a second insulative support member. The burner cap is electrically conductive and connected to the range top which serves as an electrical ground potential, and the spark electrode is connected to a high voltage potential through the electrical circuit for providing ignition sparks between the electrode and the burner cap. The sparks ignite the primary air/gas mixture passing through the burner ports to create the desired burner flame which is supported by the secondary ambient air.
There are many problems and disadvantages associated with known sealed gas burner assemblies, and particularly those provided with spark igniters. For example, the spark created by the electrode jumps from the electrode to the burner body and ignites the primary air-gas mixture that flows through the spark. This ignition is easily realized in a cast burner head, but more difficult to achieve in a drawn sheet metal burner cap, such as used in a sealed burner assembly, because the main portion of the electrode is contained within the burner head to protect it from food spillovers. Since only the tip of the electrode protrudes out through the electrode aperture of the burner head, there is a tendency for the spark to randomly jump to the burner body in all directions. A known attempt to overcome this problem involves adding gas pathways formed integrally with the electrode body or integral with the aperture through which the electrode protrudes. These gas pathways are so located that during sparking in random directions, the gas will hopefully become ignited within a required period of four seconds. This arrangement is not entirely reliable and the integral gas pathways create a tool maintenance problem.
Moreover, in a traditional sealed burner-type range, the burner head may be assembled to the range top either with or without fasteners. When fasteners are utilized, the burner head is attached to the range top with screws or nuts which provide a more positive sealing engagement, but is inconvenient for cleaning and maintaining the range top. In those models where fasteners are not utilized, a positive engagement between the burner head and the range top cannot be realized to prevent spillage of food from entering into the burner box therebelow.
Furthermore, in a conventional gas burner having an annular hole around the burner head, the secondary air required for proper combustion is drawn through the hole. In a sealed burner assembly, the secondary air is drawn through a gap formed between the range top and the bottom of the pan or utensil resting on the grate above the burner head. It is highly preferred to maintain the height of the grate as low as possible in order to provide an improved appearance. Since the sidewall of a sealed burner head is typically straight and has a high profile, secondary air turbulence is created at increased burner rates, along with the less cosmetically appealing appearance of a higher grate height.
Some examples of known spark ignited sealed gas burner assemblies of the type discussed above are disclosed by the Stohrer, Jr. U.S. Pat. No. 4,626,196, Kwiatek U.S. Pat. No. 4,810,188 and Kwiatek U.S. Pat. No. 4,846,671.